Occurrence and removal of intestinal parasites in two wastewater treatment plants in the south of Morocco

Background Agadir city plans to reuse treated wastewater on a large scale to irrigate these green spaces. This study aims to evaluate the risk of intestinal parasites, to which human and animal populations are exposed during the reuse of treated wastewaters. Methods Over 21 months, wastewater samples were collected in Bensergao and Mzar wastewater treatment plants, in Agadir city, southern Morocco. The occurrences and removal of intestinal parasites were inspected using the modified Bailenger method. Results The biodiversity of helminths is higher than protozoa, while the protozoa cysts are more abundant and more prevalent. Generally, the highest parasitic loads were recorded during the hot season. For raw waters, the average concentration of protozoa cysts was 173.33 +/- 70.81 cysts per L for Bensergao plant and 179.33 +/- 129.22 cysts per L for Mzar plant. However, the helminths average concentration was 48.70 +/- 39.91 eggs/larvae per L for Bensergao plant and 51.10 +/- 31.76 eggs/larvae per L for Mzar plant. The purified water of the Mzar plant does not contain parasites, unlike the Bensergao plant where a small numbers of parasites were detected, included 2.33 +/- 1.53 cysts per L for protozoa and 0.45 +/- 0.58 eggs/larvae per L for helminths. Conclusions Considering parasitological risks, the purified waters of Bensergao plant cannot be used without risks to the public health and environment. In contrast, the purified waters and the purified waters disinfected by ultraviolet radiation from the Mzar plant can be used safely to water the green spaces of Agadir city.